Download Layers of the Atmosphere

Layers of the Atmosphere
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The atmosphere is
divided into layers
according to major
changes in its
temperature.
Gravity holds the
layers of the
atmosphere on the
surface of the Earth.
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The amount of air
pressure at a given
altitude is dependent
upon the weight of
the atmosphere above
that point.
The higher you go
then, the lower the air
pressure.
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Layer closest to Earth
Height varies
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18-20 km at equator
 6-8 km at the poles

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Almost all weather
occurs in this layer
Density decreases as
height increases and
temperature decreases
as the air thins.
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Radiant energy from
sunlight heats the
Earth’s surface. The
ground then reradiates
that heat to warm the
air above it.
Temperature decreases
as distance from the
ground increases.
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Convection currents
carry warm air upward
 Watch the following
videos about
convection:
http://www.youtube.com
/watch?v=yZ3mYotx7ac

http://www.youtube.com
/watch?v=arp_4UJS2c
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Temperature
decreases about 6.5ºC
for every kilometer
increase in altitude
Average temperature
at surface is 17ºC
Temperature at top of
troposphere is about
-51ºC.
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Transition layer
between the
troposphere and the
layer above it
At about 12 km
The troposphere and
the tropopause
together make up the
lower atmosphere.
Anvil cloud: The “anvil” forms at
the tropopause.
photo by king nikochan on Flickr
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Above the tropopause
up to about 50 km
In the lower
stratosphere the
temperature remains
constant and very
cold (~ -60˚C)
Generally eastwardblowing horizontal
winds form the jet
stream
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The ozone (O3) layer
is found in the
stratosphere
Sometimes called the
ozonosphere, it occurs
from 16-50 km in
altitude.
The ozone layer
shields the Earth’s
surface from harmful
UV radiation
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As ozone absorbs
radiation it heats up,
causing the increase in
temperature of the
stratosphere with
increasing altitude.
Ozone is toxic to
living things, so it is
harmful when found
near ground level.
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Transition layer between the stratosphere and the
layer above it.
~ 18˚C
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50-80 km above the
Earth
Temperatures
decrease as altitude
increases, down to
about -100˚C
Although the density
of air is quite low, it is
still enough to protect
the Earth from most
meteoroids (turning
them into meteors)
Peekskill Fireball, October 9, 1992

The transition between
the mesosphere and the
above layer is the
mesopause.
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How hot or cold
something is
A measure of how fast
a substances
molecules are moving
A measure of the
average kinetic energy
of a substance

Why do things feel
hot or cold to us?
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Directly above
the mesopause
Extends from about 90 km to
between 500 and 1,000 km
above the Earth
Temperatures climb
sharply in the lower
thermosphere then level off
and hold fairly steady with
increasing altitude
Temperatures in the upper
thermosphere can range
from about 500° C to 2,000°C
or higher depending on
solar activity.
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Despite the high
temperature it would
feel very cold to us.
Why?
The air density is so low
that most of the
thermosphere is what
we normally think of as
outer space
The space shuttle and
the International Space
Station both orbit Earth
within the
thermosphere
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The lower part of the thermosphere
Solar radiation (x-rays and UV rays) cause electrons
to escape from atoms and molecules creating ions
(electrically charged particles)
AM radio waves can be sent great distances by
bouncing them off the ions in the ionosphere
At the top of the thermosphere
 Altitude varies from 500-1,000 km as the thickness of
the thermosphere varies
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The highest layer of the
atmosphere
From the top of the
thermopause up to 10,000 km
Sometimes considered to be
the upper layer of the
thermosphere
Air atoms and molecules are
constantly escaping to space
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Hydrogen and
helium are the main
components and are
only present at
extremely low
densities.
Where many
satellites orbit the
Earth.
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